The company says a controller device failed Monday night in one of four steam generators attached to Indian Point 3. Spokesman Jerry Nappi says the cause was not clear and the device will be replaced.

He says he does not know when the reactor will be returned to the grid.

Entergy says Indian Point 2, the other reactor at the Buchanan site, continued at full power.

Indian Point 2 is the first nuclear reactor in the country to operate with an expired license. The Nuclear Regulatory Commission said the reactor could continue to operate while its renewal is under review.

Meanwhile, the Utility Workers of America says Indian Point workers have authorized a strike when their contract expires Jan. 17. Nappi says negotiations are underway.